The present invention relates to a device for checking the contents of a container for a non-self-leveling supply substance, such as lubricant, grease or the like. The container includes a stirring blade that is movable about an axis of rotation for delivering the supply substance to a consuming receiver, for example the suction chamber of a lubrication pump, and for freeing the supply substance of air inclusions. If appropriate the container is provided with an associated scraper for scraping the supply substance from the container wall and from the stirring blade. The container is also provided with a measuring unit for measuring the level of the supply substance contained therein.
In checking, in particular of low level monitoring, of the contents of containers for highly viscous supply substances, such as lubricant, grease or the like, such as for example are used in connection with central lubricating pumps, problems arise due to the high rigidity of the supply substances since it no longer behaves in a self-leveling manner. This applies inter alia in particular to greases starting at Class 2 of the consistency classification of the National Lubricating Grease Institute (NLGI) or DIN 51 818. In the case of a supply of these substances, it cannot be readily assumed that a flat surface is present in the container which could serve for measuring the level of fill.
Conventionally a rotating stirring blade is used to free the supply substance of air inclusions and supply the substance to the suction chamber of the receiving device. On the surface of the supply substance, peak and valley-like formations are generated because the rotational movement of the stirring blade always pushes the supply substance ahead of itself. The formation of the peaks and valleys, under some circumstances, may even be augmented through the measures for scraping off the supply substance from the stirring blade. The conditions are similar in the case of a rotating scraper for scraping the supply substance from the container wall. Therefore, the use of measuring units, which are known per se, and rely on the principle of reflection, is not possible. Solutions of this problem by use of a follower plate disposed on the surface of the supply substance for the purpose of leveling it, have the disadvantage that a portion of the useful contents is lost. Furthermore, with such a level-smoothing solutions, the expenditures in terms of construction and the other costs generated thereby are relatively high.
DE 44 33 170 A1 discloses a unit for monitoring low levels in a lubrication supply container. The unit comprises a stirring blade with a holder, pivotably articulated thereon for a position transmitter. The principle of monitoring in this unit is that, by means of a position sensor, the position of the position transmitter is acquired depending on whether or not a direct mechanical reciprocal interaction exists between the position transmitter and the supply substance.